Co-sulfurized alkylphenols and fatty acid esters as ashless antiwear additives for lubricating oils

ABSTRACT

A superior antiwear additive for ashless lubricating oil compositions is found in the co-sulfurized product of a C7-C40 alkylphenol and a fatty acid ester of a C10-C30 fatty acid and a C1-C30 alcohol.

United States Patent 1 1 Kennedy 5] Oct. 28, 1975 CO-SULFURIZED ALKYLPHENOLS AND 2,346,826 4/1944 Cook et a1. 242/482 x FATTY ACID ESTERS s ASHLESS 2,417,283 3/1947 Zimmer et a1. 252/48.6 ANTIWEAR ADDITIVES FOR 2,644,810 7/1953 Beretras 252/48.6 x 3,320,163 5/1967 Abbott et al 252/48.2

LUBRICATING OILS 3,817,971 6/1974 Carlson et a1 252/48.6 x

Brian R. Kennedy, San Rafael, Calif.

Chevron Research Company, San Francisco, Calif.

Filed: Feb. 4, 1974 Appl. No.: 439,494

Inventor:

Assignee:

US. Cl 252/48.6; 252/48 Z; 260/137 Int. Cl. C10M 1/38; C07G 17/00 Field of Search 252/48.6, 48.2

References Cited UNITED STATES PATENTS 11/1939 Smith 252/48.6

Primary Examiner-Delbert E. Gantz Assistant Examiner-Andrew H. Metz Attorney, Agent, or Firm-G. F. Magdeburger; C. J. Tonkin [57] ABSTRACT A superior antiwear additive for ashless lubricating oil compositions is found in the co-sulfurized product of a C C alkylphenol and a fatty acid ester of a C, C fatty acid and a C,C alcohol.

10 Claims, No Drawings Gl-SUlLlFUl ZED ALKYLPHENOLS AND FATTY AUID ESTERS AS ASI-ILESS ANTIWEAR ADDITIVES FOR LUBRICATING OILS BACKGROUND OF THE INVENTION Field of the Invention unleaded fuels. The purpose of this work was to de- 1 velop such an ashless additive. Antiwear agents also find use in functional fluids and in certain fuels.

SUMMARY OF THE INVENTION Lubricating oil, fuel and functional fluid additives which function as antiwear agents are prepared from the co-sulfurization of alkylphenol and fatty acid ester with sulfur monochloride.

Alkylphenol It is an essential feature of the invention that the phenol be monoor di-substituted with C -C alkyl groups such that the total number of carbon atoms in the alkylphenol ranges from 7 to about 50, and preferably from 7 to about 40 carbon atoms and most preferably from 18 to 40 carbon atoms. Examples of such alkyl groups include methyl, ethyl, dodecyl, n-propyl, n-butyl, sbutyl, i-butyl, hexyl, dodecyl, 2-methylhexyl and less than C -oligomers of C -C monomeric mono-olefins, such as tetrapropenyl or dibutyl groups. Examples of such alkylated phenols include methylnonylphenol, dodecylphenol, dipentylphenol, ethylphenol, propyldecylphenol, amyloctylphenol, heptylphenol, methylpolypropenylphenol, ethylpolyisobutenylphenol, tetrapropenylphenol, etc.

Fatty Acid Ester The fatty acid esters which find use in the present in vention are ethylenically unsaturated. Consequently, the fatty acid and/or the alcohol is unsaturated. The fatty acid contains from 10 to about 30 carbon atoms. Examples of the fatty acids include unsaturated monoethenoid acids such as oleic acid, C H COOH, palmitoleic acid, C, l-I COOH, petroselinic acid, C H COOI-I, erucic acid, C H COOH, gadoleic acid, C I-I COOH, vaccenic acid, C H COOH, and other naturally occurring and synthetic acids of the general formula: C H COOH; and unsaturated polyethenoid acids such as linoleic acid C, H COOH. Also included are saturated acids such as nundecanoic, C I-I COOH, lauric acid, C H COOH, myristic acid, C H COOH, palmitic acid, C l-I COOI-l, stearic acid, C, H COOH, and other naturally occurring and synthetic acids of the formula C H COOI-I. Branched-chain fatty acids are also included, as well as substituted acids such as ricinoleic acid, C I-I OI-ICOOH.

Examples of the alcohols which find use within the scope of the present invention are methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, hexanol, octanol, undecanol, tetradecanol, etc. Monoethenoid and polyethenoid alcohols are also included, such as lhydroxy-3-hexene, 2-hydroxy-5,7-dodecadiene, l-hydroxy-4,7-pentadecadiene, 2-hydroxyl O- dodecosene, etc. The alcohol can be straight chain or branched chain or partially branched and partially straight chain alcohols, Substituted alcohols are also included. The alcohols are used singly or in combinations of two or more.

A particularly preferred embodiment of this invention is the product of the reaction of oleic or linoleic acid with a C -C alcohol, preferably C -C alkanol such as undecyl alcohol. 1 mole of this ester product is then sulfurized with l or more moles of sulfur monochloride, depending upon the average number of double bonds present in the ester, and l or more moles of alkylphenol. It is an essential element of the invention that either the alcohol or the fatty acid be unsaturated. This is necessary for effective sulfurization. Although the usefulness of these materials as lubricating additives is independent of any particular supposition about the structure of the sulfurized product, it is believed that the sulfurization step introduces sulfur by forming linkages with (S),, between ethylenic double bond positions. Thus, it is believed that either the alcoholic or acidic portion of the ester molecule must be unsaturated to form effective linkages with other molecules.

The esters within the scope of the present invention are illustrated by isopropyl oleate, ethyl linoleate, pentadecyl oleate, eicosyl linoleate, decenyl stearate, eicosenyl laurate, propyl linoleate, pentadecenyl linoleate, undecyl ricinoleate, pentadecyl tallate, etc.

Tall oil is a by-product of the sulfate process for the manufacture of wood pulp. It consists of about 50 percent resin acids. The resin obtained from various species of pine is called rosin, which is chiefly abietic acid, C d-1 0 The remaining 50 percent of tall oil consists of unsaturated fatty acids, chiefly oleic and linoleic acids. Thus, derosinified tall oil is a convenient source of these unsaturated acids. Rosin is a source of the undesirable auxiliary properties of lubricating oil additives when it is present in tall oil prior to neutralization and/or sulfurization. Derosinified tall oil is commercially available. For use in embodiments of the present invention, the derosinified tall oil contains less than 5% rosin.

The preferred sulfurizing agent is sulfur monochloride. Sulfurizing agents which introduce ash into the composition, such as phosphorous pentasulfide, are not suitable for use in the preparation of the present ashless antiwear additive. Sufficient sulfur is usually chosen to provide a minimum of 8% sulfur by weight in the product additive. Preferably the additive will contain from 5 to 18% sulfur and most preferably from 8 to 13 weight percent of sulfur.

Method of Preparation The general process for the production of cosulfurized alkylphenol and fatty acid ester of the present invention comprises the mixing of the alkylphenol with the ester and sulfur monochloride in the mole ratio of about 1-2:l:l-2, and reacting said mixture at a temperature of from about 30C to about C for a period of about 0.5 to about 5 hours. A suitable mutual solvent for the reactants, such as a hydrocarbon, is normally chosen.

Example 1 Sulfur monochloride (68 grams) was added at room temperature to a stirred solution of C -C alkanol ester of derosinified tall oil (157 grams) and 138 grams of tetrapropenylphenol in n-heptane (350 milliliters). The mixture was heated to reflux and the temperature maintained for 2 hours. n-heptane was distilled from the reaction mixture until the liquid temperature reached about 165C. This temperature was maintained for 2 hours. Vacuum was applied for minutes and a small amount of material distilled. The mixture was cooled, 400 m lliliters of water and 400 milliliters of n-heptane were added with stirring. The aqueous layer was discarded and the n-heptane solution washed with three portions of water of 400 milliliters each. The n-heptane solution was dried over Na SO and stripped to give 292 grams of product containing 9.2% S and 0.48% CI.

The preferred method of preparation of the present invention is the so-called heat soak method as exemplified in Example 1. In this method after an initial period of reaction at heptane reflux temperature, i.e. about 100C for about l to 3 hours, the temperature was raised to from 115C to about 160l90C and maintained for about 2-3 hours. The heat soak method assures a higher quality product of lower corrosivity and greater effectiveness.

Example 2 A derosinified tall oil ester of C -C alkanol (157 grams), tetrapropenylalkylphenol (138 grams) and nheptane (300 milliliters) were stirred at room temperature with the addition of 68 grams of sulfur monochloride over a minute period. The pot temperature rose to 55C and stirring was continued for a further 15 minutes with a nitrogen sparge and the exit gas scrubbed with aqueous KOH. The mixture was then heated under reflux for 3 hours at a pot temperature of 1l5l18C, cooled to 80C and 350 milliliters of water added. The mixture was transferred to a separatory funnel and the aqueous layer discarded. The heptane solution was washed with 3 portions of 500 milliliters of water, dried over Na SO and stripped to give 317 grams of product containing 8.86% sulfur, and 3.09 weight percent of Cl.

Example 3 Sulfur monochloride (102 grams) was added during a 1-hour period to a stirred solution of the derosinified tallate of a C -C alkanol (157 grams) and a tetrapropenylalkylphenol (138 grams) in 350 milliliters of n-heptane. The temperature rose to 45C. The reaction mixture was set aside overnight and then heated under reflux for 2 hours with a nitrogen sparge. The mixture was cooled to 80C, 350 milliliters of water was added and the stirring continued. The aqueous layer was discarded and the heptane solution washed with 3 portions of 500 milliliters of water, dried over Na SO and evaporated to give 341 grams of product containing 12.4 weight percent of sulfur and 1.3 weight percent of Example 4 Sulfur monochloride (102 grams) was added at room temperature to a stirred solution of the derosinified tallate of a C -C alkanol (157 grams) and 138 grams of a tetrapropenylphenol in 350 milliliters of nheptane. The pot temperature rose to 55C. The mixture was heated under reflux for 2 hours with a nitrogen sparge. Then the solvent was distilled from the mixture until the pot temperature reached 168C. This temperature was maintained for 2 hours and then vacuum was applied for 10 minutes and the mixture cooled. Water (200 milliliters) was added to the mixture, stirred for 15 minutes, and 400 milliliters of n-heptane were added. The aqueous layer was discarded and the nheptane solution washed with 3 portions of 1000 milliliters of water, dried over calcium sulfate and evaporated to give 314 grams of product containing 0.06 weight percent C1.

The products of Examples 1 and 2 typify low levels of sulfur with and without the heat soak, while Examples 3 and 4 exemplify high levels of sulfur without and with heat soak respectively.

Example 5 Sulfur monochloride (510 grams) was added at room temperature to a stirred solution of derosinified tallate of a C C alkanol (780 grams) and 690 grams of a tetrapropenylphenol in 1,500 milliliters of n-heptane. After addition of S Cl the temperature was raised to 80C for 30 minutes and then to reflux temperature. After refluxing for 2 hours with nitrogen sparge, the temperature was raised to l60l70C for 2 hours. The product was stripped of solvent under vacuum and washed with several portions of water. The 1,734 grams of net product contained 13.0% sulfur and 0.23% chlorme.

Example 6 Sulfur monochloride (340 grams) was added at room temperature to a mixture of 785 grams of the derosinifled tallate of a C -C alkanol and 690 grams of a tetrapropenylphenol in 1,000 milliliters of n-heptane. The mixture was heated to 80C for 30 minutes and then refluxed under nitrogen sparge for 2 hours. The temperature was raised to 160- 1 C for 2 hours and stripped of solvent. The product was washed with several 800 milliliter portions of water, dried and filtered to give 1,455 grams of product having 8.56% sulfur and 0.38% chlorine.

Additive Medium The products of this invention may be used singly or preferably in combination of 2 or more in an oil of lubricating viscosity. The lubricafing oil can be any relatively inert and stable fluid of lubricating viscosity. Such lubricating fluids are generally of viscosities of 35-50,000 Saybolt Universal Seconds (SUS) at 100F (378C). The fluid medium or oil may be derived from either natural or synthetic sources. Included among the natural hydrocarbonaceous oils are paraffin-base, naphthenic-base or mixed-base oils. Synthetic oils include polymers of various olefins, generally of from 2 to 6 carbon atoms, alkylated aromatic hydrocarbons, etc. Nonhydrocarbon oils include polyalkylene oxides, aromatic ethers, silicones, etc. The preferred lubricating media are the hydrocarbonaceous media, both natural and synthetic. Preferred are those hydrocarbonaceous oils having viscosity of about 100-4,000 SUS and particularly those having a viscosity of from ZOO-2,000 SUS at 100F. The base lubricating fluids may be used individually or in combination whenever miscible or made so by the use of mutual solvents.

The lubricating oil will be present at or greater trates however, the oil may be present at 10-75% by weight. These concentrates are diluted with additional oil prior to being placed in service to obtain the requisite concentration.

Other additives may also be present in the composition of this invention. Materials may be added for enhancing the EP efiect of the additives, or providing other desirable properties to the lubricating medium. These include such additives as rust and corrosion inhibitors, anti-oxidants, oiliness agents, detergents, rust inhibitors, viscosity index improvers, pour point depressants, etc. Usually these will be in the range of from about 0-5 weight percent, more generally in the range of from about 0-2 weight percent of the total composition. Typical additional additives found in compositions of the present invention include phenolic and aryl amine anti-oxidants and ashless dispersants such as the alkenyl succinimides.

The additives of the present invenfion will generally be present in lubricating oils in amounts of from about 0.1 to weight percent of the total composition, more usually in the amounts of from about 0.1 to 5 weight percent of the total composition.

Evaluation TABLE I Example 5 Example 6 Four-Ball Weld Pass load 190 kg 190 kg Weld load 195 kg 195 kg Timken Pass load 30 lb 35 lb Fail load 35 lb 40 lb Further EP and antiwear test results are given in Table H. The Four-ball wear test was conducted at kgs, 1800 rpm for 1 hour at 130F. In the Falex and Four-ball wear test 2 weight percent of the additive of the listed examples was placed in a neutral petroleum base oil of 496 SUS at 100F which also contained 0.1% terephthalic acid and 5% of polyisobutenylsuccinimide of tetraethylenepentamine.

TABLE II Examples 1 2 3 4 Falex ShearJbs 2250 2150 4500 4500 Falex Wear, mg 6.0 6.6 7.0 8.8 4-Ball Wear,mm 0.26 0.36 0.40

An important property of lubricating oil compositions is their resistance to oxidation, and especially viscosity increases which occur upon long exposure to high temperatures under oxidizing conditions. The results of Table III demonstrate the superiority of the additives of the present invention. Lubricating oil compo sitions containing the co-sulfurized alkylphenol and ester of Example 5 or a sulfurized alkylphenol without ester co-sulfurization, were compared at 3 weight percent. The viscosity at F of the compositions were measured before and after 10 hours oxidation. It was found that the lubricating oil composition containing sulfurized alkylphenol sufiered a percent viscosity in crease which was twice that of the co-sulfurized alkylphenobester lubricating oil composition. In addition to these additives the lubricating oil composition contained 6% of a polyisobutenyl succinimide of tetraethylenepentamine, 0.1% of terephthalic acid, 1.25% of methylene bridged alkylphenol anti-oxidant (Ethyl 728) and 1% of a di-paraffin polysulfide. The sulfurized alkylphenol of Table HI was a sulfurized tetrapropenylphenol.

In order to test the resistance toward oxidation of these lubricating compositions, they were subjected to the Oxidator B test. In this test, resistance to oxidation is measured by means of a Dornte-type oxygen absorption apparatus (R. W. Domte, Oxidation of Light Oils, Industrial and Engineering Chemistry, Vol. 28, page 26, 1936). Normally the conditions are 1 atmosphere of pure oxygen at 340F and one reports the hours to absorption of 1 liter of oxygen by 100 grams of oil. In the Oxidator B test a catalyst is used and a reference additive package is included in the oil. The catalyst is a mixture of soluble metal-naphthanate simulating the average metal analysis of used crankcase oils. Thus the Oxidator B method measures the response to conventional inhibitors in a simulated application. The longer the time required for the uptake of one liter of oxygen, the more stable the lubricating oil composition is toward oxidation.

TABLE IV Oxidation Stability Hours to 1 liter 4.] hour 5.1

of 0 uptake The results of Table IV show the relative oxidation stability of a lubricating oil composition containing 1% of the co-sulfurized alkylphenol-ester of Example 5 and a lubricating composition (A) containing 1.5% of a cosulfurized ester-olefin wherein said ester is a tallate of a C -C alkanol, as in Example 5, and 1.5% of the sulfurized alkylphenol of Table III. The basic lubricating oil compositions were otherwise the same as in Table III.

Table V presents MS Sequence IIIC Engine Test results for two compositions with and without the cow]- furized alkylphenol-fatty acid ester of the present invention. These results are compared with the SE automotive lubricating oil specifications.

TABLE V MS SEQUENCE lllC ENGINE TEST Additive SE Specifi- None 3% cation Viscosity lncr/40 hrs., 383 91 400 Viscosity lncr/64 hrs., Solid 642 Piston Varnish, Avg. 9.1 9.2 9.3 Sludge, Avg. 9.0 9.4 9.0 Oil Ring Land Varnish 4.l 6.0 6.0 Cam and Lifter Wear Average, inches .0022 .0026 .0010 Maximum, inches .0033 .0041 .0020

The lubricating compositions of Table V containing no cosulfurized alkylphenol-ester comprised 6 weight percent of a polyisobutenyl succinimide of tetraethylenepentamine, 0.05 percent of terephthalic acid, 0.4 percent of tetrapropenyl succinic acid as a 50 percent oil solution, 7 mM/kg of zinc bis(polypropylene phenyl)dithiophosphate and 11 mM/kg of zinc di(C.,- C alkyl)dithiophosphate in a neutral mineral oil. The lubricating composition of Table V containing 3 weight percent of the cosulfurized alkylphenol-ester of the present invention comprised 6 weight percent of the polyisobutenyl succinimide of tetraethylenepentamine, 0.1 percent terephthalic acid, 0.8 percent tetrapropenyl succinic acid as a 50 percent oil solution, and 1 weight percent of diparaffin polysulfide in a neutral mineral oil. Varnish and sludge ratings are on a scale from to with 10 being completely clean. The ashless lubricating composition containing 3 percent of cosulfurized alkylphenol-ester gave surprisingly superior viscosity increase control and engine cleanliness results in comparison to the typical ash-containing lubricating composition of Table V.

The results of Tables l-V demonstrate the superiority of the co-sulfurized alkylphenol-esters of the present invention over separately sulfurized ester and separately sulfurized alkylphenol for use in ashless lubricating oil compositions. Quite surprisingly, the results obtained are comparable or superior to those obtainable from lubricating oil compositions containing phosphorus or other materials producing ash residue. The excellence of the co-sulfurized alkylphenol-ester for use in ashless lubricating oils for gasoline engines is clearly established.

I claim:

1. A lubricating composition comprising a major amount of an oil of lubricating viscosity and an antiwear amount of a cosulfurized C -C alkyl phenol and fatty acid ester of a C -C fatty acid and a C -C alkanol or alkenol, said ester containing at least one site of olefinic unsaturation and wherein the mole ratio of said alkylphenol to said fatty acid ester is about 12:1.

2. A lubricating composition according to claim 1 wherein said alkylphenol and fatty acid ester are cosulfurized with sulfur monochloride.

3. A lubricating composition according to claim 2 wherein the mole ratio of alkylphenol to fatty acid ester fo sulfur monochloride is about 12:1:12.

4. A lubricating composition according to claim 3 wherein said alkylphenol contains from 18 to 40 carbon atoms.

5. A lubricating composition according to claim 4 wherein said alkylphenol is tetrapropenylphenol.

6. A lubricating composition according to claim 1 wherein said fatty acid is oleic or linoleic acid.

7. A lubricating composition according to claim 1 wherein said fatty acid ester is derosinified tall oil ester.

8. A lubricating composition according to claim 7 wherein said ester is a derosinified tall oil ester of a C C alkanol.

9. A lubricating composition according to claim 1 wherein said functional amount is from about 0.1 to about 15% by weight of the lubricating composition.

10. A lubricating composition according to claim 1 wherein said co-sulfurized alkylphenol and fatty acid ester contains from 5 to 18% sulfur by weight. 

1. A LUBRICATING COMPOSITION COMPRISING A MAJOR AMOUNT OF AN OIL LUBRICATING VISCOSITY AND AN ANTIWEAR AMOUNT OF A COSULFURIZED C7-C40 ALKYL PHENOL AND FATTY ACID ESTER OF A C10-C30 FATTY ACID AND A C1-C30 ALANOL, OR SAID LAKENOL ESTER CONTAINING AT LEAST ONE SITE OF OLEFINIC UNSATURATION AND WHEREIN THE MOLE RATIO OF SAID ALKLPHENOL TO SAID FATTY ACID ESTER IS ABOUT 1-2:1.
 2. A lubricating composition according to claim 1 wherein said alkylphenol and fatty acid ester are co-sulfurized with sulfur monochloride.
 3. A lubricating composition according to claim 2 wherein the mole ratio of alkylphenol to fatty acid ester to sulfur monochloride is about 1-2:1:1-2.
 4. A lubricating composition according to claim 3 wherein said alkylphenol contains from 18 to 40 carbon atoms.
 5. A lubricating composition according to claim 4 wherein said alkylphenol is tetrapropenylphenol.
 6. A lubricating composition according to claim 1 wherein said fatty acid is oleic or linoleic acid.
 7. A lubricating composition according to claim 1 wherein said fatty acid ester is derosinified tall oil ester.
 8. A lubricating composition according to claim 7 wherein said ester is a derosinified tall oil ester of a C10-C18 alkanol.
 9. A lubricating composition according to claim 1 wherein said functional amount is from about 0.1 to about 15% by weight of the lubricating composition.
 10. A lubricating composition according to claim 1 wherein said co-sulfurized alkylphenol and fatty acid ester contains from 5 to 18% sulfur by weight. 